Spherical cow

A spherical cow is a humorous metaphor for highly simplified scientific models of complex real life phenomena.[1][2] The implication is that theoretical physicists will often reduce a problem to the simplest form they can imagine in order to make calculations more feasible, even though such simplification may hinder the model's application to reality. The concept is well enough known that it is sometimes referred to in scientific discourse without explanation.[3]

Milk production at a dairy farm was low, so the farmer wrote to the local university, asking for help from academia. A multidisciplinary team of professors was assembled, headed by a theoretical physicist, and two weeks of intensive on-site investigation took place. The scholars then returned to the university, notebooks crammed with data, where the task of writing the report was left to the team leader. Shortly thereafter the physicist returned to the farm, saying to the farmer, "I have the solution, but it only works in the case of spherical cows in a vacuum".

It is told in many variants,[5] including a spherical horse in a vacuum, from a joke about a physicist who said he could predict the winner of any horse race, provided it involved perfectly elastic spherical horses moving through a vacuum.[6][7]

The joke sometimes shows up outside the physics community. In an episode of the sitcom The Big Bang Theory, the joke is told with a slight variation, the punchline mentioning "spherical chickens in a vacuum".[8]

In the 1997 British Channel Four series Brass Eye, host Chris Morris campaigns against spherical cows. He distributes flyers and gets public opinion on the use of spherical cows as food, implying that such cows exist and are secretly being sold in British shops. Response was universally negative, but none of the respondents shown on the program questioned the veracity of the spherical cow's existence.

Consider a Spherical Cow is the title of a 1988 book about problem solving using very simplified models,[9] and "Spherical Cow" was chosen as the codename for the Fedora 18Linux distribution.[10]